Automatic optical projection scanner with improved activation controlling mechanism

ABSTRACT

An automatic bar code symbol reading system provides a hand-supportable laser bar code reading device which can be used in either an automatic hands-on mode of operation, or in an automatic hands-free mode of operation. The system includes a scanner support frame for supporting the hand-supportable device in a user-selected mounting position, and permits complete gripping of its handle portion for use in the hands-on mode of operation. In general, the hand-supportable bar code reading device has long-range and short-range modes of object detection, bar code presence detection and bar code symbol reading. Pursuant to one illustrative embodiment, the long-range mode is automatically selected when the hand-supportable bar code reading device is placed within the scanner support stand during the automatic hands-free mode of operation. When the hand-supportable bar code reading device is picked up from the support stand and used in its hands-on mode of operation, the short-range mode is automatically selected to provide CCD-like scanner emulation. When used in either mode of operation, the automatic bar code reading device is capable of reading, in a consecutive manner, one or more bar code symbols on an object, while preventing multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon the bar code symbol. The automatic bar code symbol reading system of the present invention is disclosed in several different mounting arrangements at a point-of-sale station, illustrating novel methods of reading bar code symbols using the automatic hand-supportable optical scanning device of the present invention.

RELATED CASES

[0001] This Application is a continuation of patent application Ser. No.09/726,544, filed Dec. 5, 2000, now U.S. Pat. No. 6,499,664, which is acontinuation of patent application Ser. No. 09/368,470 filed Aug. 4,1999, now U.S. Pat. No. 6,188,793, which is a continuation of patentapplication Ser. No. 09/204,176 filed Dec. 3, 1998, now U.S. Pat. No.6,283,375, which is a continuation of patent application Ser. No.08/921,870 filed Aug. 25, 1997, now U.S. Pat. No. 5,925,871, which is acontinuation of patent application Ser. No. 08/561,479 filed on Nov. 20,1995, now issued as U.S. Pat. No. 5,661,292, which is a continuation ofpatent application Ser. No. 08/293,695 filed on Aug. 19, 1994, nowissued as U.S. Pat. No. 5,468,951, which is a continuation of patentapplication Ser. No. 07/898,919, filed on Jun. 12, 1992, and now issuedas U.S. Pat. No. 5,340,973.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to laser scanningsystems, and more particularly to a bar code symbol reading system inwhich an automatic hand-supportable laser scanner can be interchangeablyutilized as either a portable hand-held laser scanner in an automatic“hands-on” mode of operation, or as a stationary laser projectionscanner in an automatic “hands-free” mode of operation.

[0004] 2. Description of Related Art

[0005] Bar code symbols have become widely used in many commercialenvironments such as, for example, point-of-sale (POS) stations inretail stores and supermarkets, inventory and document tracking, anddiverse data control applications. To meet the growing demands of thisrecent innovation, bar code symbol readers of various types have beendeveloped for scanning and decoding bar code symbol patterns, and forproducing symbol character data for use as input in automated dataprocessing systems.

[0006] In general, prior art bar code symbol readers using laserscanning mechanisms can be classified into two categories. The firstcategory includes systems having lightweight, portable hand-held laserscanners which can be supported in the hand of a user. The userpositions the hand-held laser scanner at a specified distance from theobject bearing the bar code symbol, manually activates the scanner toinitiate reading, and then moves the scanner over other objects bearingbar code symbols to be read. Prior art bar code symbol readersillustrative of this first category are disclosed in U.S. Pat. No.4,387,297 to Swartz; U.S. Pat. No. 4,575,625 to Knowles; U.S. Pat. No.4,845,349 to Cherry; U.S. Pat. No. 4,825,057 to Swartz, et al.; U.S.Pat. No. 4,903,848 to Knowles; U.S. Pat. No. 5,107,100 to Shepard, etal.; U.S. Pat. No. 5,080,456 to Katz, et al.; and U.S. Pat. No.5,047,617 to Shepard et al.

[0007] The second category of bar code symbol readers includes systemshaving stationary laser scanners supported on or built into an immovablestructure such as a supermarket counter. These laser scanners arereferred to as countertop scanners and typically utilize a moving laserbeam to create a laser scan pattern. Each object bearing a bar codesymbol to be read is oriented by the user and then moved through thelaser scan pattern in order to read the bar code symbol. Prior art barcode symbol scanners illustrative of this second category are disclosedin U.S. Pat. No. 4,086,476 to King; U.S. Pat. No. 4,960,985 to Knowles;and U.S. Pat. No. 4,713,532 to Knowles.

[0008] While prior art hand-held and stationary laser scanners haveplayed an important role in the development of the bar code symbolindustry, these devices have, however, suffered from a number ofshortcomings and drawbacks. For example, hand-held laser scanners,although portable and lightweight, are not always convenient to use inassembly-line applications where the user processes bar coded objectsover an extended period of time, or where the user requires the use ofboth hands in order to manipulate the objects. In some applications,hand-held laser scanners are difficult to manipulate whilesimultaneously moving objects or performing other tasks at apoint-of-sale terminal. Stationary laser scanners, on the other hand,provide a desired degree of flexibility in many applications by allowingthe user to manipulate bar coded objects with both hands. However, bytheir nature, stationary laser scanners render scanning large, heavyobjects a difficult task as such objects must be manually moved into orthrough the laser scan field.

[0009] Attempting to eliminate the problems associated with the use ofhand-held and stationary laser scanners, U.S. Pat. No. 4,766,297 toMcMillan discloses a bar code symbol scanning system which combines theadvantages of hand-held and stationary fixed laser scanners into asingle scanning system which can be used in either a hands-on orhands-free mode of operation.

[0010] The bar code symbol scanning system in U.S. Pat. No. 4,766,297includes a portable hand-held laser scanning device for generatingelectrical signals descriptive of a scanned bar code symbol. In thehands-on mode of operation, a trigger on the hand-held laser scanningdevice is manually actuated each time a bar code symbol on an object isto be read. The system further includes a fixture having a head portionfor receiving and supporting the hand-held laser scanning device, and abase portion above which the head portion is supported at apredetermined distance. In the hands-free mode of operation, thehand-held laser scanning device is supported by the fixture head portionabove the fixture base portion in order to allow objects bearing barcode symbols to pass between the head and base portions of the fixture.In order to detect the presence of an object between the head and baseportions of the fixture, the fixture also includes an object sensoroperably connected to the hand-held laser scanning device. When theobject sensor senses an object between the head portion and the baseportion, the object sensor automatically initiates the hand-held laserscanning device supported in the fixture to read the bar code symbol onthe detected object.

[0011] While the bar code symbol scanning system of U.S. Pat. No.4,776,297 permits reading of printed bar code information using either aportable “hands-on” or stationary “hands-free” mode of operation, thissystem suffers from several significant shortcomings and drawbacks aswell.

[0012] In particular, in the hands-on mode of operation, scanning barcode symbols requires manually actuating a trigger each time a bar codesymbol is to be read. In the hands-free mode of operation, scanning barcode symbols requires passing the object bearing the bar code betweenthe head and base portions of the fixture. However, in many instanceswhere both hands are required to manipulate a bar coded object, theobject is too large to be passed between the head and base portions ofthe fixture and thus scanning of the bar code symbol is not possible.

[0013] Thus, there is a great need in the bar code symbol reading artfor a bar code symbol reading system which overcomes the above describedshortcomings and drawbacks of prior art devices and techniques, whileproviding greater versatility in its use.

OBJECTS AND SUMMARY OF THE INVENTION

[0014] Accordingly, it is a primary object of the present invention toprovide a fully automatic bar code symbol reading system having anautomatic hand-supportable laser scanning device which can be used aseither a portable hand-supported laser scanner in an automatic hands-onmode of operation, or as a stationary laser projection scanner in anautomatic hands-free mode operation.

[0015] It is another object of the present invention to provide such anautomatic bar code symbol reading system, in which one or more bar codesymbols on an object can be automatically read in a consecutive manner.

[0016] A further object is to provide such an automatic bar code symbolreading device, in which the automatic hand-supportable bar code(symbol) reading device has an infrared light object detection fieldwhich spatially encompasses at least a portion of its visible laserlight scan field along the operative scanning range of the device,thereby improving the laser beam pointing efficiency of the deviceduring the automatic bar code reading process of the present invention.

[0017] Another object of the present invention is to provide such anautomatic bar code reading system in which a support frame is providedfor supporting the hand-supportable housing of the device in a selectedmounting position, and permitting complete gripping of the handleportion of the hand-supportable housing prior to removing it from thesupport frame.

[0018] A further object of the present invention is to provide such anautomatic bar code symbol reading system in which the hand-supportablebar code reading device has long and short-range modes of objectdetection within its object detection field. In one illustrativeembodiment, the long and short-range modes of object detection aremanually selectable by the user by manual activation of a switch on thehand-supportable housing of the device. In another illustrativeembodiment, the long-range mode of object detection is automaticallyselected when the hand-supportable bar code reading device is placedwithin the support stand during the hands-free mode of operation. Inthis illustrative embodiment, the short-range mode of object detectionis automatically selected whenever the hand-supportable bar code readingdevice is picked up from the support stand and used in its hands-on modeof operation.

[0019] A further object of the present invention is to provide such anautomatic bar code symbol reading system, in which the hand-supportablebar code reading device has long and short-range modes of bar codepresence detection within its scan field. In one illustrativeembodiment, the short-range mode of bar code presence detection ismanually selectable by manual activation of a switch on thehand-supportable housing of the device. In another illustrativeembodiment, the short-range mode of bar code presence detection isautomatically selected when the hand-supportable bar code reading deviceis placed within the support stand, or alternatively, upon decoding apredesignated bar code symbol preprogrammed to induce the short-rangemode of bar code presence detection. In the short-range mode of bar codepresence detection, the automatic bar code reading device not onlydetects the presence of a bar code within the scan field by analysis ofcollected scan data, but it further processes the collected scan data toproduce digital count data representative of the measured time intervalbetween bar and/or space transitions. Bar code symbols present withinthe short-range of the scan field, produce scan data having timeinterval characteristics failing within a prespecified timing datarange. Using the results of this analysis, only bar bode symbols scannedwithin the short-range field are deemed “detected,” and only bar codesymbols detected within the short-range of the scan field activate thedecoding module of the device and thus enable bar code symbol reading.

[0020] A further object of the present invention is to provide such anautomatic bar code symbol reading system in which the hand-supportablebar code reading device has long and short-range modes of bar codesymbol reading within its scan field. In one illustrative embodiment,the long and short-range modes of bar code symbol reading are manuallyselectable by the user by manual activation of a switch on thehand-supportable housing of the device. In another embodiment, thelong-range mode of object detection is automatically selected when thehand-supportable bar code reading device is placed within the supportstand during the hands-free mode of operation, or alternatively, upondecoding a predesignated bar code symbol preprogrammed to induce themode of bar code symbol reading. In this illustrative embodiment, theshort-range mode of object detection is automatically selected wheneverthe hand-supportable bar code reading device is picked up from thesupport stand and used in its hands-on mode of operation. In thisshort-range mode of bar code symbol reading, the only decoded bar codesymbols residing within the short-range portion of the scan field, aredeemed “read”.

[0021] It is another object of the present invention to provide anautomatic hand-supportable bar code reading device which has both longand short-range modes of object detection and bar code symbol reading,automatically selectable by placing the hand-supportable device withinits support stand and removing it therefrom. With this particularembodiment of the present invention, the automatic bar code symbolreading system can be used in various bar code symbol readingapplications, such as, for example, charge coupled device (CCD) scanneremulation and bar code “menu” reading in the hands-on short-range modeof operation, and counter-top projection scanning in the hands-freelong-range mode of operation.

[0022] An even further object of the present invention is to provide anautomatic hand-supportable bar code reading device which preventsmultiple reading of the same bar code symbol due to dwelling of thelaser scanning beam upon a bar code symbol for an extended period oftime.

[0023] A further object of the present invention is to provide apoint-of-sale station incorporating the automatic bar code symbolreading system of the present invention.

[0024] It is a further object of the present invention to provide anautomatic hand-supportable bar code reading device having a controlsystem which has a finite number of states through which the device maypass during its automatic operation, in response to diverse conditionsautomatically detected within the object detection and scan fields ofthe device.

[0025] It is yet a further object of the present invention to provide aportable, fully automatic bar code symbol reading system which iscompact, simple to use and versatile.

[0026] Yet a further object of the present invention is to provide anovel method of reading bar code symbols using a automatichand-supportable laser scanning device.

[0027] These and further objects of the present invention will becomeapparent hereinafter and in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] For a fuller understanding of the objects of the presentinvention, the Detailed Description of the Illustrated Embodiment of thePresent Invention will be taken in connection with the drawings,wherein:

[0029]FIG. 1 is a perspective view of the illustrative embodiment of theautomatic bar code symbol reading system of the present invention,showing the hand-supportable laser bar code symbol reading devicesupported within the scanner support stand for automatic hands-freeoperation;

[0030]FIG. 1A is an elevated front view of the automatic bar code symbolreading system of FIG. 1, showing the light transmission window of thehand-supportable bar code symbol reading device while supported withinthe scanner support stand;

[0031]FIG. 1B is a plan view of the automatic bar code symbol readingsystem shown in FIG. 1;

[0032]FIG. 1C is a bottom view of the automatic bar code symbol readingsystem shown in FIG. 1;

[0033]FIG. 2 is a perspective view of the automatic hand-supportable barcode symbol reading device of the system hereof, shown being used in theautomatic hands-on mode of operation;

[0034]FIG. 2A is a elevated, cross-sectional side view taken along thelongitudinal extent of the automatic bar code symbol reading device ofFIG. 2, showing various hardware and software components utilized inrealizing the illustrative embodiment of the automatic hand-supportablebar code symbol reading device of the present invention;

[0035]FIG. 2B is a cross-sectional plan view taken along line 2B-2B ofFIG. 2A, showing the various components used in realizing theillustrative embodiment of the automatic bar code symbol reading device;

[0036]FIG. 2C is an elevated partially fragmented cross-sectional viewof the head portion of the automatic hand-supportable bar code symbolreading device of the present invention, illustrating anelectro-optional arrangement utilized in transmitting pulsed infraredlight signals over the object detection field of the device;

[0037]FIG. 2D is an elevated partially fragmented cross-sectional viewof the head portion of the automatic hand-supportable bar code symbolreading device of the present invention, illustrating theelectro-optical arrangement utilized in producing the object detectionfield of the device;

[0038]FIG. 3 is an elevated side view of the hand-supportable bar codesymbol reading device of the illustrative embodiment of the presentinvention, illustrating the spatial relationship between the objectdetection and scan fields of the device, and the long and short-rangesof programmed object detection, bar code presence detection, and barcode symbol reading;

[0039]FIG. 3A is a plan view of the automatic hand-supportable bar codesymbol reading device taken along line 3A-3A of FIG. 3;

[0040]FIG. 4 is a system block functional diagram of the automatichand-supportable bar code symbol reading device of the presentinvention, illustrating the principal components integrated with thesystem controller thereof;

[0041]FIG. 5 is a block functional diagram of a first embodiment of theobject detection mechanism for the automatic hand-supportable bar codesymbol reading device of the present invention;

[0042]FIG. 6 is a block functional diagram of a second embodiment of theobject detection mechanism for the automatic hand-supportable bar codesymbol reading device of the present invention;

[0043]FIGS. 7A and 7B, taken together, show a high level flow chart of asystem control program (i.e. Main System Control Routine) containedwithin the control system of the automatic bar code symbol readingdevice, illustrating various courses of programmed system operation thatthe illustrative embodiment may undergo;

[0044]FIGS. 8A and 8B, taken together, show a high level flow chart ofan auxilliary system control program (i.e. Auxilliary System ControlRoutine with Range Selection), which provides the hand-supportableautomatic bar code symbol reading device of the present invention withseveral selectable modes of object detection, bar code presencedetection and bar code symbol reading;

[0045]FIG. 9 is a state diagram illustrating the various states that theautomatic hand-supportable bar code symbol reading device of theillustrative embodiment may undergo during the course of its programmedoperation;

[0046]FIG. 10 is a perspective view of the support frame of the scannersupport stand of the present invention;

[0047]FIG. 10A is a perspective view of the base plate of the scannersupport stand of the present invention, with the adapter module mountedthereon;

[0048]FIG. 10B is a perspective, partially broken away view of theassembled scanner support stand of the present invention, showing thescanner cable, power supply cable and communication cable operablyassociated therewith and routed through respective apertures formed inthe scanner support frame;

[0049]FIGS. 11A through 11D are perspective views of a point-of-salesystem, showing the scanner support stand of the present inventionsupported on a horizontal countertop surface and operably connected toan electronic cash register, with the automatic hand-supportable barcode symbol reading device being used in its hand-held short-range modeof operation;

[0050]FIGS. 12A and 12B are perspective views illustrating the stepcarried out during the installation of the scanner support stand of thepresent invention onto a vertical counter wall surface;

[0051]FIG. 13 is an elevated side view of the automatic bar code symbolreading system of the present invention, shown mounted onto the verticalcounter surface of FIGS. 12A and 12B;

[0052]FIG. 13A is a plan view of the automatic bar code symbol readingsystem of the present invention taken along line 13A-13A of FIG. 13;

[0053]FIG. 13B is a cross-sectional view of the scanner support stand ofthe present invention, taken along line 13B-13B of FIG. 13;

[0054]FIG. 13C is a cross-sectional view of the assembled scanner stand,taken along line 13C-13C of FIG. 15A;

[0055]FIG. 14 is perspective views showing the scanner support standmounted on a vertical counter wall surface, and the automatichand-supportable bar code symbol reading device being used in itsautomatic hands-free long-range mode of operation;

[0056]FIGS. 15A and 15B are perspective views showing the scannersupport stand mounted on a vertical counter wall surface, and theautomatic hand-supportable bar code symbol reading device being used inits automatic hand-held short-range mode of operation;

[0057]FIG. 16 is a perspective view of a point-of-sale station accordingto the present invention, showing the scanner support stand pivotallysupported above a horizontal counter surface by way of a pedestal basemounted under an electronic cash register, and the automatichand-supportable bar code symbol reading device received in the scannersupport stand and being used in its automatic hands-free long-range modeof operation;

[0058]FIGS. 17A and 17B are perspective views of a point-of-sale stationaccording to the present invention, showing the scanner support standpivotally supported above a horizontal counter surface by way of thepedestal base illustrated in FIG. 16, and the automatic hand-supportablebar code symbol reading device being used in its automatic hand-heldshort-range mode of operation;

[0059]FIG. 18 is an elevated side view of the point-of-sale system ofFIGS. 16A, 16B and 17, illustrating the rotational freedom of thescanner support stand about the x axis of the privotal joint assembly;

[0060]FIG. 18A is an elevated, partially cross-sectional view of thebase plate of the scanner support stand and the pivotal joint assemblyconnecting the scanner support stand to the pedestal base so as toprovide three-degrees of freedom to the scanner support stand withrespect to the stationary pedestal base;

[0061]FIG. 18B is a partially fragmented view of the scanner supportstand, pivotal joint assembly and pedestal base taken along the y axisof the pivotal joint assembly, illustrating the rotational freedom ofthe scanner support stand about the y axis; and

[0062]FIG. 18C is a perspective view of the scanner support stand andpedestal base assembly taken along the z axis of the pivotal jointassembly, illustrating the rotational freedom of the scanner supportstand about the z axis of the pivotal joint assembly.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT OF THE PRESENTINVENTION

[0063] In FIG. 1, the automatic laser bar code symbol reading system ofthe present invention, is illustrated. As shown, automatic bar codesymbol reading system 1 comprises a portable, automatic hand-supportablebar code symbol reading device 2 operably associated with scannersupport stand 3 of the present invention. Operable interconnection ofhand-supportable bar code reading device 2 and scanner support stand 3is achieved by a flexible multiwire scanner cable 5 extending from barcode symbol device 2 into scanner support stand 3. Operableinterconnection of scanner support stand 3 and a host system 6 (e.g.electronic cash register system, data collection device, etc.) isachieved by a flexible multiwire communications cable 7 extending fromscanner support stand 3 and plugged directly into the data-inputcommunications port of host system 6. In the illustrative embodiment,electrical power from a low voltage power supply (not shown) is providedto scanner support stand 3 by way of a flexible power cable 8.

[0064] As illustrated in FIGS. 1 through 1C, scanner support stand 3 isparticularly adapted for receiving and supporting hand-supportable barcode reading device 2 in a selected position without user support, thusproviding a stationary, automatic hands-free mode of operation. Ingeneral, hand-supportable bar code reading device 2 includes anultra-light weight hand-supportable housing 9 having a contoured handleportion 9A and a head portion 9B. As will be described in greater detailhereinafter, head portion 9B encloses electro-optical components whichare used to generate and project a visible laser beam through a lighttransmissive window 10, and to repeatedly scan the projected laser beanacross a scan field 11 defined external to the hand-supportable housing.

[0065] As illustrated in FIGS. 1 through 1C, scanner support stand 3includes a support frame 12 which comprises a base portion 12A, a headportion support structure 12B, handle portion support structure 12C anda finger accommodating recess 12D. As shown, base portion 12A has alongitudinal extent and is adapted for selective positioning withrespect to a support surface, e.g. countertop surface, counter wallsurface, etc. Head portion support structure 12B is operably associatedwith base portion 12A, for receiving and supporting the head portion ofthe hand-supportable bar code reading device. Similarly, handle portionsupport structure 12C is operably associated with base portion 12A, forreceiving and supporting the handle portion of the hand-supportable barcode symbol reading device. In order that the user's hand can completelygrasp the handle portion of the hand-supportable bar code reading device(that is, prior to removing it off and away from the scanner supportstand as illustrated in FIG. 14A), finger accommodating recess 12D isdisposed between head and handle portion support structures 12B and 12Cand above base portion 12A of the support frame. In this way, fingeraccommodating recess 12D is laterally accessible as shown in FIG. 13, sothat when the handle and head portions 9A and 9B are received within andsupported by handle portion support structure 12B and head portionsupport structure 12C, respectively, the fingers of a user's hand can beeasily inserted through finger accommodating recess 12D and completelyencircle the handle portion of the hand-supportable device, asillustrated in FIG. 14A.

[0066] A more detailed description of the structure, functions andoperation of the scanner support stand of the present invention will beprovided hereinafter referring to FIGS. 10 through 16B. However,referring to FIGS. 1 and 10 through 13, attention will be first accordedto the illustrative embodiment of the automatic hand-supportable barcode reading device of the invention.

[0067] As illustrated in FIGS. 2 through 2B in particular, head portion9B continuously extends into contoured handle portion 9A at an obtuseangle a which, in the illustrative embodiment, is about 146 degrees. Itis understood, however, that in other embodiments obtuse angle .alpha. amay be in the range of about 135 to about 180 degrees. As this ergonomichousing design is sculpted (i.e. form-fitted) to the human hand,automatic hands-on scanning is rendered as easy and effortless as wavingones hand. Also, this ergonomic housing design eliminates the risks ofmusculoskeletal disorders, such as carpal tunnel syndrome, which canresult from repeated biomechanical stress commonly associated withpointing prior art gun-shaped scanners at bar code symbols, squeezing atrigger to activate the laser scanning beam, and then releasing thetrigger.

[0068] As illustrated in FIGS. 2 through 3A, the head portion of housing9 has a transmission aperture 13 formed in upper portion of front panel14A, to permit visible laser light to exit and enter the housing, aswill be described in greater detail hereinafter. The lower portion offront panel 14B is optically opaque, as are all other surfaces of thehand-supportable housing.

[0069] As illustrated in FIGS. 2, 3 and 3A in particular, automatichand-supportable bar code reading device 2 generates two differentfields external to the hand-supportable housing, in order to carry outautomatic bar code symbol reading according to the principles of thepresent invention. The first field, referred to as the “object detectionfield”, indicated by broken and dotted lines, is provided externally tothe housing for detecting energy reflected off an object bearing a barcode symbol, located within the object detection field. The secondfield, referred to as the “scan field”, having at least one laser beamscanning plane is provided external to the housing for scanning a barcode symbol on an object in the object detection field. In the preferredembodiment, such scanning is achieved with a visible laser beam whichproduces laser scan data which is collected for the purpose of detectingthe presence of a bar code symbol within the scan field, andsubsequently reading (i.e. scanning and decoding) the detected bar codesymbol.

[0070] In general, detected energy reflected from an object duringobject detection, can be optical radiation or acoustical energy, eithersensible or non-sensible by the user, and may be either generated fromthe automatic bar code reading device or an external ambient source. Aswill be described in greater detail hereinafter, the provision of suchenergy is preferably achieved by transmitting a wide beam of pulsedinfrared light away from transmission aperture 13 and substantiallyparallel to longitudinal axis 15 of the head portion of thehand-supportable housing. In the preferred embodiment, the objectdetection field, from which such reflected energy is collected, isdesigned to have, a narrowly diverging pencil-like geometry ofthree-dimensional volumetric expanse, which is spatially coincident withat least a portion of the transmitted infrared light beam. This featureof the present invention ensures that an object residing within theobject detection field will be illuminated by the infrared light beam,and that infrared light reflected therefrom will be directed generallytowards the transmission aperture of the housing where it can beautomatically detected to indicate the presence of the object within theobject detection field. In response, a visible laser beam isautomatically generated within the head portion of the housing,projected through the transmission aperture and repeatedly scannedacross the scan field, within which at least a portion of the detectedobject lies. At least a portion of the scanned laser light beam will bescattered and reflected off the object and directed back towards andthrough light transmissive window 10 for collection and detection withinthe head portion of the housing, and subsequently processed in a mannerwhich will be described in detail hereinafter. To ensure that the usercan quickly align the visible laser beam with bar code symbol on thedetected object, the object detection field is designed to spatiallyencompass at least a portion of the scan field along the operativescanning range of the device, as illustrated in FIGS. 3 and 3A. Thisstructural feature of the present invention provides the user with anincreased degree of control, as once an object is detected, minimal timewill be required by the user to point the visible laser beam towards thebar code symbol for scanning. In effect, the laser beam pointingefficiency of the device is markedly improved during the automatic barcode reading process, as it is significantly easier for the user toalign the laser beam across the bar code symbol upon object detection.

[0071] To more fully appreciate the mechanisms employed in order togenerate the object detection and scan fields of the automatic bar codereading device of the present invention, reference is best made to theoperative elements contained within the hand-supportable housing of thedevice.

[0072] As shown in FIG. 4, automatic bar code reading device 2 comprisesa number of system components, namely, an object detection circuit 16,laser scanning mechanism 17, photoreceiving circuit 18, analogto-digital (A/D) conversion circuit 19, bar code presence detectionmodule 30, bar code scan range detection module 21, symbol decodingmodule 22, data format conversion module 23, symbol character datastorage unit 24, and data transmission circuit 25. In addition, amagnetic field sensing circuit 26 is provided for detecting scannersupport stand 3, while a manual switch 27 is provided for selecting longor short-range modes of object detection, bar code presence detectionand/or bar code symbol reading, which will be described in great detailhereinafter. As illustrated, these components are operably associatedwith a programmable system controller 28 which provides a great degreeof versatility in system control, capability and operation. Thestructure, function and advantages of this system controller will becomeapparent hereinafter.

[0073] In the illustrated embodiment, system controller 28, bar codepresence detection module 20, bar code scan range detection module 21,symbol decoding module 22, and data format conversion module 23 arerealized using a single programmable device, such as a microprocessorhaving accessible program and buffer memory, and external timingcircuitry. It is understood, however, that any of these elements may berealized using separate discrete components as will be readily apparentto those with ordinary skill in the art.

[0074] Automatic hand-supportable bar code reading device 2 alsoincludes power receiving lines 29 which lead to conventional powerdistribution circuitry (not shown) for providing requisite power to eachof the system components, when and for time prescribed by the systemcontroller. As illustrated, power receiving lines 29 run alongside datacommunication lines 30 and are physically associated with multi-pinconnector plug 31 at the end of flexible scanner cable 5. An on/offpower switch or functionally equivalent device (not shown) may beprovided externally of the hand-supportable housing to permit the userto selectively energize and deenergize the device. In the illustrativeembodiment, power delivered through flexible scanner cable 5 to the barcode symbol reading device is continuously provided to system controller28 so as to continuously enable its operation, while only biasingvoltages and the like are provided to all other system components. Inthis way, each system component must be activated (i.e. enabled) by thesystem controller in accordance with its preprogrammed system controlroutine.

[0075] In accordance with the present invention, the purpose of theobject detection circuit is to determine whether an object (e.g.,product, document, etc.) is present or absent from the object detectionfield over particular time intervals specified by the system controller.When an object is detected within the object detection field, the objectdetection circuit produces first control activation signal A₁=1, whichlike all control activation signals, is provided as input to systemcontroller 28. As will be described in greater detail hereinafter,depending on the particular stage of the system control process, thesystem controller will respond to this event by causing the bar codereading device to undergo a transition from the object detection stateto the bar code symbol (presence) detection state. In FIGS. 5 and 6, twodifferent techniques are disclosed for detecting the presence of anobject within the object detection field.

[0076] In FIG. 5, an “active” object detection circuit 16A is shown. Inessence, this circuit operates by transmitting a pulsed infrared (IR)light signal forwardly into the object detection field. First controlactivation signal A₁ is generated upon receiving a reflection of thetransmitted signal from an object residing within the object detectionfield. As illustrated, object detection circuit 16A is realized as an IRsensing circuit which comprises a synchronous receiver/transmitter 33and an infrared LED 34 which generates a 940 nanometer pulsed signal ata rate of 15.0 KHZ. This pulsed IR signal is transmitted throughfocusing lens 35 to illuminate the object detection field. When anobject is present within the object detection field, a reflected IRpulse signal is produced from the surface of the object, spatiallyfiltered by aperture stop 65B and focused through focusing lens 36 ontophotodiode 37. Notably, (i) selection of the optical characteristics ofaperture stop 65B and lens 36 and (ii) the placement of photodiode 37(with integrally formed lens 36) behind aperture stop 65B, directlydetermine the geometric characteristics of the object detection field.Consequently, these optical parameters are selected so as to provide anobject detection field which, as hereinbefore explained, spatiallyencompasses at least a portion of the scanning field along the operativescanning range of the device. As illustrated in FIG. 5, the output ofphotodiode 37 is converted to a voltage by current-to-voltage amplifier38, and the output thereof is provided as input to synchronousreceiver/transmitter 33 which synchronously compares the received IRsignal with the transmitted IR signal to determine whether an object ispresent in or absent from the object detection field. If the object ispresent in the object detection field, then synchronousreceiver/transmitter 33 produces first control activation signal A₁=1,indicative of this condition. Upon generation of first controlactivation signal A₁=1, the system controller activates the operation oflaser scanning mechanism 17, photoreceivjng circuit 18, A/D conversioncircuit 19, and bar code presence detection module 20 according to apreprogrammed system control routine, the details of which will bedescribed hereinafter.

[0077] In FIG. 6, a “passive” object detection circuit 10B is shown. Inessence this circuit operates by passively detecting ambient lightwithin the object detection field. First control activation signal A₁ isgenerated upon receiving light of different intensity reflected off anobject within the object detection field. As illustrated objectdetection circuit 16B is realized as a passive ambient light detectioncircuit which comprises a pair of photodiodes 39 and 40, that senseambient light gathered from two spatially overlapping parts of theobject detection field using focussing lenses 41 and 42, respectively.Notably, the optical characteristics of focusing lenses 41 and 42 andthe placement of photodiodes 39 and 40 relative to lenses 41 and 42 willcollectively determine the geometric characteristics of the objectdetection field. Consequently, these optical parameters will be selectedto provide an object detection field which spatially encompasses atleast a portion of the scanning field along the operative scanning rangeof the device. The output signals of photodiodes 39 and 40 are convertedto voltages by current-to-voltage amplifiers 43 and 44 respectively, andare provided as input to a differential amplifier 45. The output ofdifferential amplifier 45 is provided as input to a sample and holdamplifier 46 in order to reject 60 Hz and 120 Hz noise. Output signal ofamplifier 46 is provided as input to a logarithmic amplifier 47 tocompand signal swing. The output signal of logarithmic amplifier 47 isprovided as input to a differentiator 48 and then to a comparator 49.The output of comparator 49 provides first control activation signal A₁.When an object is present in the object detection field, the output ofcomputer 49 provides control activation signal A₁=1.

[0078] Alternatively, the automatic bar code reading device of thepresent invention can be readily adapted to sense ultrasonic energyreflected off an object present within the object detection field. Insuch an alternative embodiment, object detection circuit 16 is realizedas an ultrasonic energy transmitting/receiving mechanism. In the headportion of hand-supportable housing 9, ultrasonic energy is generatedand transmitted forwardly of the housing head portion into the objectdetection field. Then, ultrasonic energy reflected off an object withinthe object detection field is detected closely adjacent the transmissionwindow using an ultrasonic energy detector. Preferably, a focusingelement is disposed in front of the detector in order to effectivelymaximize the collection of reflected ultrasonic energy. In suchinstances, the focusing element essentially determines the geometricalcharacteristics of the object detection field of the device.Consequently, as with the other above-described object detectioncircuits, the energy focusing (i.e. collecting) characteristics of thefocusing element will be selected to provide an object detection fieldwhich spatially encompasses at least a portion of the scan field.

[0079] For purposes of illustration, object detection circuit 16 shownin FIG. 5, is provided with two different modes of detection, namely, along-range mode of object detection and a short-range mode of objectdetection. As shown in FIG. 4, these modes are set by the systemcontroller using mode enable signals E_(IRT)=0 and E_(IRT)=1,respectively. When induced into the long-range mode of object detection,the IR sensing circuit will generate first control activation signalA₁=1 whenever an object has been detected within the operative range ofthe object detection field, independent of the particular distance atwhich the object resides from the transmissive window. When induced intothe short-range mode of object detection, the IR sensing circuit willgenerate first activation control signal. A₁=1 only when an object isdetected at a distance within the short-range of the object detectionfield.

[0080] As schematically indicated in FIGS. 3 and 3A, the long-rangespecification for object detection is preferrably preselected to be thefull or entire range of sensitivity provided by IR sensing circuit 16A(e.g. 0 to about 10 inches). Preferrably, the short-range specificationfor object detection is preselected to be the reduced range ofsensitivity provided by the IR sensing circuit when mode enable signalE_(IRT)=1 is provided to the desensitization port of synchronousreceiver/transmitter 33. In the illustrated embodiment, the short-rangeof object detection is about 0 to about 3 inches or so to provideCCD-like scanner emulation. As will become apparent hereinafter, theinherently limited depth and width of field associated with theshort-range mode of object detection prevents laser scanning mechanism17 from flooding the scan field with laser scanning light and thusinadvertently detecting undesired bar code symbols. Particular uses towhich object detection range selection can be put, will be described ingreater detail hereinafter with reference to FIGS. 11A through 16B inparticular.

[0081] As illustrated in FIG. 4, laser scanning mechanism 17 comprises alight source 50 which, in general, may be any source of intense lightsuitably selected for maximizing the reflectively from the object'ssurface bearing the bar code symbol. In the illustrative embodiment,light source 50 comprises a solid-state visible laser diode (VLD) whichis driven by a conventional driver circuit 51. The wavelength of visiblelaser light produced from the laser diode is preferably about 670nanometers. In order to repeatedly scan the produced laser beam over ascan field having a predetermined spatial extent in front of the headportion of the housing as illustrated in FIGS. 3 and 3A, a planarscanning mirror 52 is oscillated back and forth by a stepper motor 53driven by a conventional driver circuit 54. However, one of a variety ofconventional laser scanning mechanisms may be alternatively used withexcellent results.

[0082] To selectively activate laser light source 50 and scanning motor53, the system controller provides laser diode enable signal E_(t) andscanning motor enable signal E_(n) as input to driver circuits 51, and54, respectively. When enable signal E_(t) is a logical “high” level(i.e., E_(t)=1) a laser beam is generated and projected through thelight transmissive window 10 and when E.sub._(n) is a logical highlevel, the laser beam is repeatedly scanned across the scan field.

[0083] When a bar code symbol on an object is within the scan field atthe time of scanning, the incident laser light on the bar code will bescattered and reflected. This scattering/reflection process produces alaser light return signal of variable intensity which represents aspatial variation of light reflectively characteristic of the spacedapart pattern of bars comprising the bar code symbol. Photoreceivingcircuit 18 detects at least a portion of the reflected laser light ofvariable intensity. Upon detection of this reflected laser light,photoreceiving circuit 18 produces an analog scan data signal D₁indicative of the detected light intensity.

[0084] In the illustrative embodiment, photoreceiving circuit 18generally comprises laser light collection optics 55, which focusreflected laser light for subsequent detection by a photoreceiver 56having, mounted in front of its sensor, a frequency selective filter 57which only transmits optical radiation of wavelengths up to a small bandabove 670 nanometers. Photoreceiver 56, in turn, produces an analogsignal which is subsequently amplified by preamplifier 58 to produceanalog scan data signal D₁. In combination, laser scanning mechanism 17and photoreceiving circuit 18 cooperate to generate analog scan datasignals D.sub.₁ from the scan field, over time intervals specified bythe system controller. As will be illustrated hereinafter, these scandata signals are used by bar code presence detection module 20, bar codescan range detection module 21, and symbol decoding module 22 to performparticular functions.

[0085] As illustrated in FIG. 4, analog scan data signal D₁ is providedas input to A/D conversion circuit 19. As is well known in the art, A/Dconversion circuit 19 processes analog scan data signal D₁ to provide adigital scan data signal D₂ which resembles, in form, a pulse widthmodulated signal, where logical “1” signal levels represent spaces ofthe scanned bar code and logical “0” signal levels represent bars of thescanned bar code. A/D conversion circuit 19 can be realized by anyconventional A/D circuit well known to those with ordinary skill in theart. Digitalized scan data signal D₂ is then provided as input to barcode presence detection module 20, bar code scan range detection module21 and symbol decoding module 22.

[0086] The purpose and function of bar code presence detection module 20is to determine whether a bar code is present in or absent from the scanfield over particular time intervals specified by the system controller.When a bar code symbol is detected in the scan field, bar code presencedetection module 20 generates second control activation signal A₂ (i.e.,A₂=1) which is provided as input to the system controller, as shown inFIG. 4. Preferably, bar code presence detection module 20 is realized asa microcode program carried out by the microprocessor and associatedprogram and buffer memory, described hereinbefore. The function of thebar code presence detection module is not to carry out a decodingprocess, but rather to rapidly determine whether the received scan datasignals represent a bar code symbol residing within the scan field.

[0087] There are a number of ways in which to achieve bar code presencedetection through a programming implementation. For example, in thepreferred embodiment, bar code presence detection module 20 detects thefirst and second borders of the bar code symbol “envelope”. This isachieved by first processing a digital scan data signal D.sub.₂ toproduce digital “count” and “sign” data. The digital count data isrepresentative of the measured time interval (i.e. duration) of eachsignal level occurring between detected signal level transitions whichoccur in digitized scan data signal D.sub.₂. The digital sign data, onthe other hand, indicates whether the signal level between detectedsignal level transitions is either a logical “1”, representative of aspace, or a logical “0”, representative of a bar within a bar codesymbol. Using the digital count and sign data, the bar code presencedetection module identifies the first and second borders of the bar codeenvelope, and thereby determines whether or not the envelope of a barcode symbol is represented by the scan data collected from the scanfield. When a bar code symbol envelope is detected, the bar code symbolpresence detection module provides second control activation signal A₂=1to the system controller. As will be described in greater detailhereinafter, second control activation signal A.sub.₂=1 causes thedevice to undergo a transition from bar code presence detection state tobar code symbol reading state.

[0088] Similar to the object detection circuit described above, the barcode presence detection module is provided with two different modes ofdetection, namely: a long-range mode of bar code presence detection anda short-range mode of bar code presence detection. As shown in FIG. 4,these long and short-range modes are set by the system controller usingmode select enable signals E_(4CD)=0 and E_(4CD)=1, respectively. Wheninduced into the long-range mode of detection, the bar code presencedetection module will generate second control activation signal A₂=1whenever the envelope of a bar code symbol has been detected, despitethe particular distance the bar code is from the light transmissivewindow. However, when induced into the short-range mode of detection,the bar code presence detection module will generate second controlactivation signal A₂=1 only when the envelope of a bar code symbol hasbeen detected and when the associated digital count (i.e. timing) dataindicates that the detected bar code resides within the short-rangeportion of the scan field.

[0089] Similar to long-range specification for object detection,long-range specification for bar code presence detection is preselectedto be the entire operative scanning range available to the device. In anillustrated embodiment, this range can be from about 0 to about 10inches from the transmission aperture, depending on the optics employedin the laser scanning mechanism and the response characteristics of thephotoreceiving circuit. These long and short-range specifications areschematically indicated in FIGS. 3 and 3A. In the preferred embodiment,short-range specification for bar code presence detection is preselectedto be the same range selected for short-range object detection (e.g.approximately 0 to about 3 inches from the transmission aperture). Aswill become apparent hereinafter, the inherently limited depth and widthof field associated with the short-range mode of bar code symboldetection, prevents the reading of detected bar code symbols residingoutside the short-range portion of the scan field.

[0090] Unlike the bar code symbol presence detection module, the purposeand function of bar code scan range detection module 21 is not to detectthe presence of a bar code symbol in the scan field, but rather todetermine the range (i.e. distance) at which a detected or decoded barcode symbol resides from the light transmissive window of the housing.As will be explained in greater detail hereinafter, this data processingmodule operates upon digital scan data signal D₂ which has beenpreviously utilized by either the bar code symbol detection module, orthe symbol decoding module depending on the state of the system.

[0091] When the system is induced into its short-range mode of bar codepresence detection, bar code presence detection 5 module 20 does notautomatically produce and provide second control activation signal A₂=1to the system controller upon the detection of a bar code symbol in thescan field. Rather, when a bar code symbol has been detected, the barcode presence detection module first provides to the system controller,a second control activation signal A_(2a)=1, indicative of a detectedbar code in the scan field. Then, bar code scan range detection module21 analyzes digital count data D_(C1) produced by the bar code presencedetection module, to determine at what range the detected bar codesymbol resides from the light transmissive window. If scan rangedetection module 21 determines that the detected bar code symbol islocated within the prespecified short-range portion of the scan field,then it provides second control activation signal A₂=1 to the systemcontroller; otherwise, the scan range detection module produces secondcontrol activation signal A_(2b)=0. Only when both control activationsignals A_(2a)=1 and A_(2b)=1 are received by the system controller inthis mode, does A₂=1 and thus the bar code reading device caused toundergo a transition from bar code symbol presence detection state tobar code symbol reading state.

[0092] Returning to FIG. 4, the function of symbol decoding module 22 isto process, scan line by scan line, the stream of digitized scan dataD₂, in an attempt to decode a valid bar code symbol within apredetermined time period allowed by the system controller. In generalwhen symbol decoding module 22 successfully decodes a bar code symbolwithin the predetermined time period, symbol character data D₃(typically in ASCII code format) corresponding to the decoded bar codesymbol is produced. Thereupon, a third control activation signal A₃=1 isproduced by the symbol decoding module and is provided to the systemcontroller in order to perform its system control functions.

[0093] Similar to the bar code presence detection module, the symboldecoding module is provided with two different modes of detection,namely: a long-range mode and a short-range mode of bar code symboldecoding. When the system is induced into its short-range mode of barcode symbol decoding, symbol decoding module 22 does not automaticallygenerate third activation signal A₃=1 upon decoding a valid bar codesymbol. Rather, when a bar code symbol has been successfully decoded,the symbol decoding unit first provides to the system controller, athird activation control signal A_(3a)=1, indicative of a decoded barcode symbol in the scan field. Then, bar code scan range detectionmodule 21 analyzes digital count data D_(C2) produced by the symboldecoding module, to determine at what range (i.e. distance) the decodedbar code symbol resides from the transmission aperture. If the bar codescan range detection module determines that the decoded bar code symbolresides within the prespecified short-range portion of the scan field,then it provides third control activation signal A₃=1 to the systemcontroller; otherwise, bar code scan range detection module producesthird control activation signal A₃=0. Only when both control activationsignals A_(3a)=1 and A_(3b)=1 are received by the system controller inthis mode, does A₃=1 and thus the bar code reading device caused toundergo a transition from the bar code symbol reading state to thesymbol character data transmission/storage state.

[0094] The long-range and short-range modes of bar code symbol detectionand decoding described above each require the use of bar code scan rangedetection to determine whether or not the detected or decoded bar codesymbol resides in the short or long-range portion of the scan field. Assuch, the use of this scan data processing technique permits the systemof the present invention to condition the occurrence of particularevents within the system control program. This feature of the presentinvention will be illustrated in great detail hereinafter whendescribing auxilliary system control routine of FIGS. 8A and 8B.

[0095] As will be illustrated in greater detail hereinafter withreference to FIGS. 8 and 8A, the system controller provides enablesignals E_(2C), E_(0S) and E_(0T) to data format conversion module 23,data storage unit 24 and data transmission circuit 25, respectively, atparticular stages of its control program. As illustrated in FIG. 4,symbol decoding module 22 provides symbol character data D₃ to dataformat module 23 to convert data D₃ into two differently formatted typesof symbol character data, namely D₄ and D₅. Format-converted symbolcharacter data D₅ is of the “packed data” format, particularly adaptedfor efficient storage in data storage unit 24. Format-converted symbolcharacter data D₅ is particularly adapted for data transmission to hostcomputer system 6 (e.g. an electronic cash register). When symbolcharacter data D₄ is to be converted into the format of the users choice(based on a selected option mode), the system controller provides enablesignal E_(0S) to data storage unit 24, as shown in FIG. 4. Similarly,when format converted data D₅ is to be transmitted to host device 6, thesystem controller provides enable signal E_(0T) to data transmissioncircuit 25. Thereupon, data transmission circuit 24 transmitsformat-converted symbol character data D₅ to host computer system 6, viathe data transmission lines of flexible scanner connector cable 5.

[0096] In order to select either the long or short-range mode of object(and bar code range detection, the hand-supportable bar code readingdevice is provided with both manual and automated mechanisms foreffectuating such range selections.

[0097] For example, a manual switch 27 is mounted on the top surface ofthe handle portion of the housing, so that long and short-range modes ofobject and bar code range detection can be selected by simply depressingthis switch with ones thumb while handling the bar code reading device.This switch provides control activation signal A₄=1 to the systemcontroller, which in turn generates the appropriate mode enable signalE_(IRT).

[0098] In the illustrated embodiment, magnetic field sensing circuit 26is operably associated with the system controller to automaticallygenerate control activation signal A₄=1 when the hand-supportable barcode reading device is not supported within scanner support stand 3. Aswill be described in greater detail hereinafter, scanner support stand 3includes a means for producing a magnetic field in proximity with eitherone of the head or handle portion support structures 12A and 12B. Withthis arrangement, magnetic field sensing circuit 26 generates controlactivation signal A₄=1 when the magnetic field is sensed while thehand-supportable bar code reading device is received within the scannersupport stand. Additionally, a indicator light can be provided on thehousing of the hand-supportable device to visually indicate theparticular mode which has been manually or automatically selected.

[0099] In general, magnetic sensing circuit 26 comprises a magnetic fluxdetector 60, a preamplifier and a threshold detection circuit. Magneticflux detector 60 produces as output an electrical signal representativeof the intensity of detected magnetic flux density in its proximity.When housing 9 is received and supported in scanner support stand 3, asshown, for example, in FIGS. 1, 13, 15, and 17, magnetic flux detector60 is in position to detect magnetic flux emanating from a magnetic barfixedly mounted within the handle portion support structure of thescanner support stand. The produced electrical signal from the magneticflux detector is amplified by the preamplifier whose output is comparedto a predetermined threshold maintained in the threshold detectorcircuit. If the intensity of the detected magnetic flux exceeds thethreshold, long-range control activation signal A₄=1 is provided to thesystem controller.

[0100] As illustrated in FIG. 2, magnetic flux detector 60 is mounted tothe rearward underside surface of the handle portion of housing 9. Inthe illustrated embodiment, a ferrous bar 61 is interiorly mounted tothe underside surface of the housing handle portion as shown. As will bedescribed in greater detail hereinafter, this arrangement facilitatesreleasable magnetic attachment of the hand-supportable housing to themagnetic bar fixedly installed in the handle portion support structureof the scanner support stand. Preferably, a hole 61A is drilled throughferrous bar 61 to permit installation of magnetic flux detector 60 sothat magnetic flux emanating from the handle portion support structureis detectable when the hand-supportable housing is placed within thescanner support stand, as shown in FIGS. 1, 13, 15, and 17. In thisconfiguration, magnetic flux detector 60 is in proximity with the sourceof magnetic flux (i.e. magnetic bar in the scanner support stand) andthus long-range control activation signal A₄=1 is provided to the systemcontroller. In response, the system controller enables long-range objectdetection (i.e. E_(IRT)=0). When the hand-supportable housing is removedfrom the scanner support stand as shown in FIGS. 2, 11C, 14B and 16B,the intensity of the magnetic flux from the scanner support stand is nolonger sufficient in strength to produce long-range mode activationsignal A₄=1; instead, short-range control activation signal A₄=0 isprovided to the system controller. In response, the system controllerenables short-range object detection (i.e. E_(IRT)=1), and the automatichand-supportable bar code reading device emulates the operational rangeof a CCD scanner.

[0101] As illustrated in FIG. 2A, a thin ferrous plate 62 is exteriorlyapplied to the underside of the head portion of the hand-supportablehousing. As will be described in greater detail hereinafter, thefunction of ferrous elements 61 and 62 is to provide a means by whichthe plastic hand-supportable housing can be magnetically attracted bymagnetic elements installed within head and handle portion supportstructures 12B and 12C when the bar code reading device is placed in thescanner support stand.

[0102] It is understood that there are a variety of ways in which toconfigure the above described system components within thehand-supportable housing of the automatic bar code reading device, whilesuccessfully carrying out of functions of the present invention. InFIGS. 2A through 2D, one preferred arrangement is illustrated.

[0103] In FIG. 2A, the optical arrangement of the system components isshown. Specifically, visible laser diode 50 is mounted in the rearcorner of circuit board 63 installed within the head portion of thehousing, Stationary concave mirror 55 is mounted centrally at the frontend of circuit board 63, primarily for the purpose of collecting laserlight reflected off detected objects. Notably, the height of concavemirror 55 is such as not to block transmission aperture 13. Mounted offcenter onto the surface of concave mirror 55, is a very small secondmirror 64 for directing the laser beam to planar mirror 52 which isconnected to the motor shaft of scanning motor 53, for joint oscillatorymovement therewith. As shown, scanning motor 53 is mounted centrally atthe rear end of circuit board 63. In the opposite rear corner of circuitboard 63, photodetector 56 and frequency selective filter 57 aremounted.

[0104] In operation, laser diode 50 adjacent the rear of the headportion, produces a laser beam which is directed in a forward directionto the small stationary mirror 64 and is then reflected back tooscillating mirror 52. Oscillating mirror 52 directs the laser beamthrough transmission aperture 13 and light transmissive window 10, whilerepeatedly scanning the laser beam across the scan field. Under thecontrol of the user, the visible laser beam is aligned with a bar codesymbol on the detected object, so that the laser beam scans the bar andspace pattern thereof. A portion of the scattered laser light reflectedfrom the bar code symbol is directed back through the light transmissivewindow and towards oscillating mirror 52, which also acts as a lightretroreflective mirror. Oscillating mirror 52 then directs the reflectedlaser light to stationary concave collecting mirror 55 at the forwardend of the head portion of the hand-supportable housing. The laser lightcollected from the concave mirror 55 is then directed to photodetector56 to produce an electrical signal representative of the detectedintensity of the laser light reflected off the bar code symbol.

[0105] As illustrated in FIG. 2C, IR LED 34 and photodiode 37 aremounted to circuit board 63, in front of stationary concave mirror 55and in a slightly offset manner from longitudinal axis 15 of the headportion of the housing. Apertures 65A and 65B are formed in opaquehousing panel 14B, below transmission aperture 13, to permittransmission and reception of pulsed IR energy signals, as hereinbeforedescribed. In order to shield IR radiation from impinging on photodiode37 via the housing, a metallic optical tube 66 having an aperture of 67encases photodiode 37. The dimensions of aperture 67, the placement ofIR LED 34 and its radiation transmission characteristics collectivelywill determine the radiation pattern of the transmitted IR signal fromaperture 65A in the housing. In order to collect pulsed IR radiationfrom the object detection field of designed geometry, photodiode 37 islocated at a selected distance behind aperture stop 65B formed in opaquehousing panel 14B, as shown in FIG. 2D. By selecting the dimensions ofaperture stop 65B and the placement of photodiode 37 (and integrallyformed lens 36) behind aperture stop 65B, the desired geometricalcharacteristics and the object detection field can be directlydetermine, as described hereinbefore.

[0106] In order to prevent optical radiation slightly below 670nanometers from passing through transmission aperture 13 and enteringthe housing, light transmissive window 10 is realized as a plasticfilter lens is installed over the transmission aperture. This plasticfilter lens has optical characteristics which transmit only opticalradiation from slightly below 670 nanometers. In this way, thecombination of plastic filter lens 10 at the transmission aperture andfrequency selective filter 57 before photoreceiver 56 cooperate to forma narrow band-pass optical filter having a center frequency f_(c)=670nanometers. By permitting ony optical radiation associated with thevisible laser beam to enter the housing, this optical arrangementprovides improved signal-to-noise ratio for detected scan data signalsD₁.

[0107] In addition to the above-described optical and electro-opticalcomponents, circuit board 63 carries all other electronic components andassociated circuitry used in realizing IR object detection circuit 16A,scanning mechanism 17, photoreceiving circuit 18, and A/D conversion 19.With respect to the other system components, a second circuit board 69is mounted within the handle portion of the housing, as shown in FIGS.2A and 2B. The function of circuit board 69 is to carry electroniccomponents and associated circuitry used in realizing bar code presencedetection module 20, bar code scan range detection module 21, symboldecoding module 22, data format conversion module 23, data storage unit24, data transmission circuit 25, magnetic field detection circuit 26,manual range/mode selection switch 27, and system controller 28. Allconductors associated with flexible multiwire scanner cable 5 areelectrically connected to circuit board 69 in a manner well know in theart. Electrical communication between circuit boards 63 and 69 isrealized using a plurality of electrical wires jumping across thesecircuit boards.

[0108] Having described the detailed structure and internal functions ofthe automatic bar code reading device of the illustrative embodiment,the operation of its system controller will now be described withreference to system block diagram shown in FIG. 4, and to Blocks A to CCshown in FIGS. 7A and 7B.

[0109] Beginning at the START block of Main System Control Routine ofFIG. 7A and proceeding to Block A, bar code reading device 2 isinitialized. This involves activating (i.e. enabling) IR sensing circuit16A and the system controller. The system controller, on the other hand,deactivates (i.e. disables) the remainder of activatable systemcomponents, e.g. laser diode 50, scanning motor 53, photoreceivingcircuit 18, A/D conversion circuit 19, bar code presence detectionmodule 20, bar code scan data range detection module 21, symbol decodingmodule 22, data format conversion module 23, data storage unit 24, anddata transmission circuit 25. All timers T₁, T₂, T₃, T₄ and T₅ (notshown) maintained by the system controller are reset to t=0 seconds.

[0110] Proceeding to Block B, the system controller checks to determinedwhether control activation signal A₁=1, is received from IR sensingcircuit 16A. If this signal is not received, then the system controllerreturns to the START block. If signal A₁=1 is received, indicative thatan object has been detected within the object detection field, then thesystem controller proceeds to Block C, at which timer T₁ is started andis permitted to run for a preset time period, e.g. 0≦T₁≦3 seconds, andtimer T₂ is started and permitted to run for a preset time period of0≦T₂≦5 seconds.

[0111] Proceeding to Block D, the system controller activates laserdiode 50, scanning motor 53, photoreceiving circuit 18, A/D conversioncircuit 19 and bar code presence detection module 20 in order to collectand analyze scan data signals D₂ for the purpose of determining whetheror not a bar code is within the scan field. Then, at Block E, the systemcontroller checks to determine whether control activation signal A₂=1 isreceived from bar code presence detection module 20 within time period1≦T₁≦3 seconds. If activation control signal A₂=1, is not receivedwithin this period, then the system controller proceeds to Block F. AtBlock F, the system controller deactivates laser diode 50, scanningmotor 53, photoreceiving circuit 18, A/D conversion circuit 19 and barcode presence detection module 20. Then the system controller remains atBlock G until it receives control activation signal A₁=0 from IR sensingcircuit 16A, indicative that the object is no longer in the objectdetection field. When this condition exists, the system controllerreturns to the START block.

[0112] If, however, the system controller receives control activationsignal A₂=1 within time period 0≦T_(1b)≦3 seconds, indicative that a barcode has been detected, then the system controller proceeds to Block H.As will be described hereinafter, this represents a transition from thebar code presence detection state to the bar code symbol reading state.Proceeding to Block H, the system controller continues activation oflaser diode 40, scanning motor 53, photoreceiving circuit 18, and A/Dconversion circuit 19, while commencing activation of symbol decodingmodule 20. At this stage, fresh bar code scan data is collected andsubjected to decode data processing. At essentially the same time, atBlock I, the system controller starts timer T3 to run for a time periodO≦T_(3b)≦1 second.

[0113] As indicated at Block J, the system controller checks todetermine whether control activation signal A₃=1 is received from thesymbol decoding module 22 within T₃=1 second, indicative that a bar codesymbol has been successfully read (i.e. scanned and decoded) within theallotted time period. If control activation signal A₃ is not receivedwithin the time period T₃=1 second, then at Block K the systemcontroller checks to determine whether control activating signal A₂=1 isreceived within time period O≦T₃≦3 seconds. If a bar code symbol is notdetected within this time period, then the system controller proceeds toBlock L to deactivate laser diode 50, scanning motor 53, photoreceivingcircuit 18, A/D conversion circuit 19, bar code presence detectionmodule 20 and symbol decoding module 22. Notably, this event causes astate transition from the bar code reading state to the object detectionstate. Thereafter, at Block M the system controller remains in theobject detection state awaiting control activation signal A₁=0,indicative that an object is no longer in the object detection field.When this condition exists, the system controller returns to the STARTblock, as shown.

[0114] If at Block K, however, the system controller receives controlactivation signal A₂=1, indicative that a bar code once again is withinthe scan field, then the system controller checks to determine whethertime period T₂ has elapsed. If it has, then the system controllerproceeds to Block L and then to the START block by way of Block M. Ifhowever time period O≦T₂≦5 seconds has not elapsed, then the systemcontroller resets timer T₃ to run once again for a time period O≦T₃≦1second. In essence, this provides the device at least anotheropportunity to read a bar code present within the scan field when thesystem controller is at control Block J.

[0115] Upon receiving control activation signal A₃₌1 from symboldecoding module 29, indicative that a bar code symbol has beensuccessfully read, the system controller proceeds to Block O. At thisstage of the system control process, the system controller continues toactivate laser diode 50, scanning motor 53, photoreceiving circuit 18and A/D conversion circuit 19, while deactivating symbol decoding module22 and commencing activation of data format conversion module 23, datastorage unit 24 and data transmission circuit 25. These operationsensure repeated scanning of the laser beam across the scan field, whilesymbol character data is being appropriately formatted and transmittedto host computer system 6 by conventional data communication processwell known in the art.

[0116] After transmission of symbol character data to the host device iscompleted, the system controller enters Block P and continues activationof laser diode 50, scanning motor 53, photoreceiving circuit 18 and A/Dconversion circuit 19, while deactivating symbol decoding module 22,data format-conversion module 23, data storage unit 24 and datatransmission circuit 25. To detect the continued presence of an objectwithin the object detection field, the system controller checks at BlockQ whether control activation signal A₁=1 is received from IR sensingcircuit 16A. If A₁=0, indicative that the object is no longer in theobject detection field, then the system controller returns to the STARTblock. If control activation signal A₁=1 is received, then at Block Rthe system controller activates bar code presence detection module 20.These events represent once again a transition from the object detectionstate to the bar code symbol presence detection state.

[0117] At Block S, the system controller starts timer T₄ to run for atime period O≦T₄≦5 seconds, and timer T₅ to run for a time period ofO≦T₅≦3 seconds. Then to determine whether a bar code symbol has beendetected within the scan field, system controller proceeds to Block T tocheck whether control activation signal A₂=1 is received. If this signalis not received with the time period O≦T₅≦3 seconds, indicative that nobar code symbol is present in the scan field, the system controllerproceeds to Block U, at which it deactivates laser diode 50, scanningmotor 53, photoreceiving circuit 18, A/D conversion circuit 19 and barcode presence detection module 20. Thereafter, the system controllerremains at Block V until the object leaves the object detection fieldand (i.e. receives control activation signal A₁=0), at which time thesystem controller returns to the START block, as shown.

[0118] If, however, at Block T control activation signal A₂₌1 isreceived, indicative that a bar code symbol has been detected in thescan field, the system controller proceeds through Blocks W and X toreactivate the symbol decoding module and start timer T₆ to run for atime period O≦T₆≦1 second. These events represent a transition from thebar code symbol detection state to the bar code symbol reading state. AtBlock Y, the system controller checks to determine whether controlactivation signal A₃=1 is received from symbol decoding module 22 withintime period O≦T₆≦1 second. If a bar code symbol is not successfully readwithin this 1 second time period, the system controller returns to BlockT to form a first loop, within which the device is permitted to detector redetect a bar code symbol within the time period O≦T₄≦5 seconds. Ifa bar code symbol is decoded within this time interval, the systemcontroller determines at Block Z whether the decoded bar code symbol isdifferent from the previously decoded bar code symbol. If it isdifferent, then the system controller returns to Block O as illustrated,to format and transmit symbol character data as described hereinabove.

[0119] If however, the decoded bar code symbol is not different than thepreviously decoded bar code symbol, then at Block AA the systemcontroller checks to determine whether timer T₆ has elapsed. If it hasnot elapsed, the system controller returns to Block T to form a secondloop, within which the device is permitted to detect or redetect a barcode symbol in the scan field and then successfully read a valid barcode symbol within the set time interval O≦T₆≦5 seconds. If, however,time T₆ lapses, then the system controller proceeds to Block BB at whichthe system controller deactivates laser diode 50, scanning motor 53,photoreceiving circuit 18, A/D conversion circuit 19, bar code presencedetection module 20, and symbol decoding module 22. Thereafter, thesystem controller remains at Block CC until control activation signalA₁=0 is received from IR sensing circuit 16A, indicative that the objectdetection field is free of any objects. At this stage, the systemcontroller returns to the START block, as shown in FIG. 7B.

[0120] The operation of automatic hand-supportable bar code readingdevice 2 has been described in connection with The Main System ControlRoutine which uses control activation signals A₁, A₂ and A₃. This systemcontrol routing operates on two basic assumptions concerning IR sensingcircuit 16A and bar code symbol presence detection module 20.Specifically, The Main System Control Routine assumes that the IRsensing circuit produces control activation signal A₁=1, whenever anobject is detected anywhere within the operative detection range of theobject detection field. It also assumes that the bar code symbolpresence detection module produces control activation signal A₂=1whenever a bar code symbol is detected anywhere within the operativescanning range of the scan field. These assumptions cause statetransitions during the operation of the automatic bar code symbolreading device, when otherwise they may not be desired in particularapplications.

[0121] For example, in some applications it may not be desirable toautomatically advance the bar code symbol reading device to its bar codepresence detection state until an object bearing a bar code is withinthe short-range portion of the object detection field, as hereinbeforedescribed. Also, it may not be desirable to automatically advance to thebar code symbol reading state until a detected bar code symbol islocated within the short-range portion of the scan field. Also, it maynot be desirable to automatically advance to the symbol character datastorage/transmission state until a decoded bar code symbol is locatedwithin the short-range portion of the scan field. Thus, in someinstances, it may be desirable to condition transition from (i) objectdetection to the bar code symbol detection state, (ii) the bar codesymbol detection state to the bar code symbol reading state, and (iii)the bar code symbol reading state to the symbol character datastorage/transmission state. Yet, in other instances, it may only bedesirable to condition only one or two of these state transitions.

[0122]FIGS. 8A and 8B illustrate The Auxilliary System Control Routinewith Range Selection which provides the automatic bar code readingdevice of the present invention with range selection capabilities forobject detection, bar code presence detection, and bar code symbolreading. These range selection functions are provided when the systemcontroller runs the Auxilliary System Control Routine in cooperationwith the Main System Control Routine described above. It is understood,however, that this Auxilliary System Control Routine may be adapted foruse with other suitable system control programs.

[0123] Beginning at the START block and proceeding to Block A of FIG.8A, the system controller intitially selects the long-range objectdetection mode by letting the IR sensing circuit operate at fullsensitivity (i.e. E_(IRT)=0). To determine whether the short-range modeof object detection, bar code symbol presence detection and bar codesymbol reading has been selected, the system controller proceeds toBlock B′ and checks whether it has received control activation signalA₄=1. As described hereinbefore in connection with FIG. 4, activationsignal A₄=1 can be generated in at least two possible ways. For example,the short-range mode may be manually selected by depressing switch 27 onthe handle portion of the housing. Alternatively, the short-range modemay be selected by simply lifting the bar code reading device out fromthe scanner support stand, as illustrated in FIGS. 2, 11C, 14B, and 16B.In either case, prior to operating the bar code reading device, it ispreferred that either the manual or automatic range mode selectionmechanism be programmably set within the system controller by way of barcode menu programming, a technique well known in the art. For purposesof illustration only, the Auxilliary System Control Routine of FIGS. 8Aand 8B will be described using the automatic range mode selectionmechanism provided by magnetic sensing circuit 26.

[0124] If control activation signal A₄=1 is received at Block B′, thenthe system controller selects short-range object detection bydesensitizing the IR sensing circuit. This is achieved by providing modeselection enabling signal E_(IRT)=1 as hereinbefore described. Thenproceeding to Block D′, the system controller enters the START block ofMain System Control Routine of FIGS. 7A and 7B. Thereafter, the controlflow proceeds as prescribed by the Main System Control Routine. Notably,whenever the control flow in the Main System Control Routine returns tothe START block of FIG. 7A, the system controller exits Main SystemControl Routine and returns to the START block of FIG. 8A.

[0125] As illustrated at Block E′ of FIG. 8A, whenever the control flowis at Blocks D, I or R in the Main System Control Routine, the systemcontroller activates bar code presence detection 20 module and bar codescan range detection module 21. Thereafter, while at any one of thesecontrol blocks, the bar code scan range detection module processes scandata signals D₂ so as to produce digital count and sign data ashereinbefore described. As indicated at Block F′, an additionalcondition is placed on control Blocks E, K and T in the Main SystemControl Routine so that a transition from the bar code presencedetection state to the bar code symbol reading state occurs only if (i)the object is detected in the short-range portion of the objectdetection field, and (ii) the bar code symbol is detected in theshort-range portion of the scan field. In terms of data processing, whenthe system control flow is at any one of such blocks in the Main SystemControl Routine and the system controller receives control activationsignal A₂=1, then the system controller also determines whether thedigital count data of the detected bar code resides within theshort-range count interval.

[0126] If the produced digital count data D_(C1) indicates that thedetected bar code symbol is located within the short-range portion ofthe scan field, then as indicated at Block G′ of FIG. 8A, the systemcontroller continues activation of the laser diode 50, scanning motor53, photoreceiving circuit 18 and A/D conversion circuit 19, whichcommencing activation of symbol decoding circuit 22. As indicated atBlock H′, whenever the control flow is at either Block J or Block Y inthe Main System Control Routine and the system controller receives thirdcontrol activation signal A_(3a)=1, then the system controllerdetermines whether the digital count data D_(C1) from the decoded barcode symbol resides within the short-range count interval (i.e. A_(3b)=1is produced from scan range detection module 21). If digital count dataD_(C2) resides within the short-range portion of the scan field, (i.e.A_(3b)=1) then as indicated at Block I′, the system controller proceedsto Blocks O or Z, respectively, in the Main System Control Routine. Ifdigital count data D_(C2) is not within the short-range portion of thescan field (i.e. A_(3b)=0), then as indicated at Block J, the systemController proceeds to Blocks K or J, respectively, in the Main SystemControl Routine.

[0127] If, however, digital count data D_(C1) produced at Block Findicates that the detected bar code symbol is not located within theshort-range portion of the scan field (i.e. A_(2b)=0), then as indicatedat Block K′ of FIG. 8A, the system controller proceeds to Blocks F, L orU, respectively, in the Main System Control Routine.

[0128] Turning attention to Block B′ of FIG. 8A, the system controllermay not receive control activation signal A₄=1 from range selectioncircuits 26 or 27, as indicated at this block. Instead, short andlong-range mode capabilities can be automatically selected by readingbar code symbols. This can be achieved by programming symbol decodingmodule 22 to recognize predesignated bar code symbols whichautomatically activate and deactivate long-range and short-range modesof object detection, bar code presence detection, and/or bar code symbolreading. This mechanism for automatic range selection is highlyadvantageous in many applications, such as, for example, reading barcode menus, CCD scanner emulation and the like.

[0129] As indicated at Block B′ in FIG. 8A, when control activationsignal A₄=1, the system controller activates the long-range mode ofobject detection by letting IR sensing circuit 16A operate at fullsensitivity (i.e. E_(IRT)=0), as indicated at Block L′. Then at BlockM′, the system controller enters the START block of Main System ControlRoutine of FIGS. 7A and 7B. As indicated at Block N′, before enteringBlock O of the Main System Control Routine, the system controllerdetermines whether the successfully read bar code symbol is a bar codesymbol which has been predesignated to activate the short-range mode ofobject detection, bar code presence detection and/or bar code symbolreading. This condition is determined by the system controller checkingwhether control activation signal A₅=1 is received from the symboldecoding module as shown in FIG. 4. If control activation signal A₅=0 isreceived by the system controller, then as indicated at Block O′, thesystem controller proceeds to Block O of the Main System ControlRoutine. If, however, control activation signal A₅=1 is received, thenas indicated at Block P′, the system controller activates theshort-range mode of object detection by desensitizing IR sensing circuit16A (i.e. E_(IRT)=0). This operation ensures that control activationsignal A₁ is produced only when an object is detected within theshort-range portion of the object detection within the short-rangeportion of the object detection field. As indicated at Block Q′ of FIG.8A, whenever the system controller is at Block D, I or R in the MainSystem control Routine. The System Controller activates bar codepresence detection module 20 and bar code scan range detection module21.

[0130] As indicated at Block R′, an additional condition is placed oncontrol Blocks E, K and T in the Main System Control Routine.Specifically, a transition from the bar code presence detection state tothe bar code symbol reading state occurs only if the detected bar codesymbol resides in the short-range portion of the scan field. Thiscondition is satisfied by the scan range detection module determiningwhether or not the digital count data of the detected bar code symbolfalls within a prespecified short-range count interval. If this digitalcount data does not fall within the short-range count interval, then asindicated at Block R′, the system controller proceeds to control BlocksF, L or U, respectfully, in the Main System Control Routine, asindicated at Block K′. If, however, the digital count data is within theprespecified short-range count interval, then control activation signalA_(2B)=1 is provided to the system controller as illustrated in FIG. 4.In this instance, both control activation signals A_(2A)=1 and A_(2B)=1are provided to the system controller so as to effectuate a transitionto the bar code symbol reading state. This event is represented at BlockS′ of FIG. 8B by the system controller continuing the activation oflaser diode 50, scanning motor 53, photoreceiving circuit 18, A/Dconversion circuit 19 and bar code scan range detection module 20, whiledeactivating bar code symbol detection module 21 and activating symboldecoding module 22.

[0131] As indicated at Block T′ of FIG. 8B, when the control flow is atBlocks J or Y in the Main System Control Routine and the systemcontroller receives control activation signal A_(3A)=1, then the systemcontroller determines whether the digital count data of the decoded barcode symbol is within the short-range count interval. If the bar codescan range detection module determines that decoded bar code symbolresides within the prespecified short-range portion of the scan field,then it provides third control activation signal A_(3B)=1 to the systemcontroller, causing the bar code reading device to undergo a transitionto the symbol character data transmission/storage state. In this case,as indicated at Block U′, before entering Block O in the Main SystemControl Routine, the symbol decoding module determines whether thedecoded bar code symbol is a short-range mode deactivation symbol. Ifthe decoded bar code is such a symbol, then as indicated at Block V′,the system controller activates the long-range mode by letting IRsensing circuit 16A operate at full sensitivity (i.e. E_(IRT)=0), whiledeactivating bar code scan range detection module 21. Thereafter, thesystem proceeds to Blocks O or Z, respectively, in the Main SystemControl Routine. If, however, the decoded bar code symbol is not ashort-range mode deactivation symbol, then as indicated at Block U′, thesystem proceeds directly to Blocks O or Z, respectively, in the MainSystem Control Routine.

[0132] If however, as indicated at Block T′ the decoded bar code symboldoes not reside within the short-range portion of the scan field, thesystem proceeds to Block X′. At this stage of the system controlprocess, the symbol decoding module determines whether the decoded codesymbol is a short-range mode deactivation symbol. If the decoded barcode symbol is such a symbol, then as indicated at Block Y′, the systemcontroller activates the long-range mode by letting IR sensing circuit16A operate at full sensitivity, while deactivating bar code scan rangedetection module. Thereafter, the system proceeds to Blocks K or T,respectively, in the Main System Control Routine. If, however, thedecoded symbol is not a short-range mode deactivation symbol, then asindicated at Block Y′, the system controller activates the long-rangemode by letting the IR sensing circuit 16A to operate at fullsensitivity, while deactivating bar code scan range detection module 21.Thereafter, the system proceeds to Blocks K or T, respectively, in theMain System Control Routine. If, however, the decoded bar code symbol isnot a short-range mode deactivation symbol, then the system directlyproceeds to Blocks I or T, respectively in the Main System ControlRoutine.

[0133] Having described the operation of the illustrative embodiment ofthe automatic hand-supportable bar code reading device of the presentinvention, it will be helpful to describe at this juncture the variousconditions which cause state transitions to occur during its operation.In this regard, reference is made to FIG. 9 which provides a statetransition diagram for the illustrative embodiment.

[0134] As illustrated in FIG. 9, the automatic hand-supportable bar codereading device of the present invention has four basic states ofoperation namely: object detection, bar code symbol presence detection,bar code symbol reading, and symbol character data transmission/storage.The nature of each of these states has been described above in greatdetail. These four states are schematically illustrated as A, B, C andD, respectively, in the state transition diagram of FIG. 9. Notably, two“extensional states” have also been provided so that the automatic barcode reading device of the illustrative embodiment is capable of readingan infinite number of consecutively different bar code symbols on aparticularly detected object (e.g. a product or apparently continuoussurface) without returning to the object detection state. Theseextensional states of operation are indicated as E and F and representbar code presence detection and bar code symbol reading operations,respectively. As described above, these operations are employed whenattempting to automatically read one or more consecutively different barcodes symbols, that is, after a first bar code symbol has beensuccessfully read utilizing operational states A through C.

[0135] As shown in FIG. 9, transitions between the various states areindicated by directional arrows. Besides each set of directional arrowsare transition conditions expressed in terms of control activationsignals (e.g. A₁, A₂ and A₃), and where appropriate, state timeintervals (e.g. T₁, T₂, T₃, T₄, T₅ and T₆). Conveniently, the statediagram of FIG. 9 expresses most simply the four basic and twoextensional operations occurring during the control flow within thesystem control program of FIGS. 7A and 7B. Significantly, the controlactivation signals A₁, A₂ and A₃ in FIG. 9 indicate which events withinthe object detection and/or scan fields can operate to effect a statetransition within the allotted time frame(s), where prescribed.

[0136] Referring now to FIGS. 10 through 10B, the scanner support standof the present invention will be described.

[0137] As illustrated in FIGS. 10 through 10B, scanner stand 3 of theillustrative embodiment comprises support frame 12 releasably connectedto a base support/mounting plate 70 by way of a snap fit fasteningmechanism illustrated in FIG. 13C. In the illustrative embodiment,support frame 12 is formed as an injection molded shell, in which handleportion support structure 12B is realized by a first support recess 71;whereas head portion support structure 12C is realized by a secondsupport recess 72. As shown in FIG. 10, first support recess 71 isdisposed above base portion 12A and inclined at a first acute angle B₁with respect thereto, while second support recess 72 is disposed abovebase portion 12B and inclined at a second acute angle B₂ with respectthereto.

[0138] As best shown in FIG. 10, first support recess 72 is formed by afirst substantially planar support surface 73 surrounded by theprojection of opposing side walls 74A and 74B and rear wall 74C,extending above planar support surface 73 in a perpendicular fashion.The function of support recess 71 is to receive and support the handleportion of hand-supportable bar code reading device. Similarly, secondsupport recess 72 is formed by a second substantially planar supportsurface 75 surrounded by the projection of opposing side walls 76A and76B and front wall surface 76C extending above planar support surface 75in a perpendicular fashion. The function of support recess 72 is toreceive and support the head portion of hand-supportable bar codereading device 2. In order that the handle portion of hand-supportablebar code reading device 2 can be received within support recess 71, rearwall 74C has a scanner cable aperture 77 which permits flexible scannercable 5 to extend freely out beyond support recess 71. Also, front wallprojection 76C is slightly lower than side wall projection 76A and 76Bto ensure that pulsed IR energy is freely transmitted from and receivedby object detection circuit 16A contained within head portion 9A. At thesame time, this structural feature of the scanner support stand ensuresthat visible laser light is projected, scanned and collected throughlight transmissive window 10 without obstruction, i.e. when theautomatic bar code reading device is operated in its automatichands-free mode, shown in FIGS. 15 and 17.

[0139] In order to ensure that the hand-supportable bar code readingdevice of the present invention will be securely, yet releasablesupported within support recesses 71 and 72 and not easily knocked outof the scanner support stand during the hands-free mode of operation,first and second magnetic elements 77 and 78 are permanently mounted tothe underside of planar support surfaces 73 and 75, respectively, asillustrated in FIG. 10B. With this arrangement, magnetic flux ofconstant intensity continuously emanates from support recesses 71 and72. As a result, when the handle and head portions of the bar codereading device are placed within support recesses 71 and 72, ferrouselement 61 in handle portion 9A is magnetically attracted to magneticelement 77, while ferrous element 62 on head portion 9B is magneticallyattracted to magnetic element 78. The magnetic force of attractionbetween these elements is selected so that a desired degree of force isrequired to lift the automatic bar code reading device out of scannersupport stand, while preventing accidental displacement of the devicefrom the scanner support stand during use in the hands-free mode ofoperation.

[0140] As illustrated in FIG. 10A, base support/mounting plate 70 isformed as a thin planar structure having perimetrical dimensionssubstantially equal to the perimetrical dimensions of the base portionof support frame 12. At the front and rear end portions 70A and 70B ofbase plate 70, a pair of projections 79 and 80 extend perpendicularly,as shown. Projections 79 and 80 have horizontal flanges 79A and 80A,respectively, which are adapted to snap fit into horizontal grooves 81and 82, formed on the interior surfaces of front and rear walls 76C and74C, as shown in FIGS. 10A, 10B and 13C.

[0141] To facilitate mounting of base plate 70 on a planar mountingsurface, as illustrated in FIGS. 12A and 12B, a pair of spaced apartmounting holes 83A and 83B are provided. To facilitate attachment ofbase plate 70 to pivotal joint assembly 97 of pedestal base 98, asillustrated in FIGS. 18A through 18C, a set of four centrally disposedmounting holes 84A, 84B, 84C and 84D are provided. To facilitate supportof base plate 70 upon a horizontal support surface, as illustrated inFIGS. 11A through 11D, a set of four rubber feet 85A, 85B, 85C and 85Dmay be adhesively applied to the underside corners of the base plate 70.

[0142] In order to eliminate the confusion produced by various cablesused to connect automatic bar code scanning device 2 to its externalpower supply (not shown) and associated host computer system 6, anadapter module 86 is concealed within the interior volume 87 containedbetween the interior surface of base portion 12A of the support frameand the upper surface of base plate 70. In the illustrated embodiment,adapter module 86 is adhesively affixed to the central portion of theupper surface of base plate 70, as illustrated in FIG. 10A. Scannerconnector 31 of flexible scanner cable 5 is plugged into scanner jack86A of the adapter module, and the communication cable connector offlexible communication cable 7 is plugged into communication jack 86B.Similarly, the power supply connector from the DC power supply cable 8is plugged into power supply jack 86C, as shown. With theseinterconnections established, support frame 12 is snapped onto baseplate 70, as hereinbefore described, flexible scanner cable 5 is routedthrough aperture 87, and flexible communication and power supply cables7 and 8 are routed through aperture 88 formed in the lower portion ofrear wall 74C of the support frame, as shown in FIG. 10B.

[0143] In the illustrative embodiment, automatic bar code reading device2 requires one regulated DC supply voltage to power the visible laserdiode and other electronic and opto-electronic components mounted oncircuit boards 63 and 69. However, in many applications, a 12V DC supplyvoltage is available at the point-of-sale station. Thus, in order toconvert the 12V DC supply voltage to a 5V DC supply voltage, a DC-to-DCvoltage converter is incorporated into adapter module 86. In this way,in addition to providing interconnections between the communicationlines of the flexible scanner and communication cables, adapter module86 also provides a means for converting the voltage level of theflexible power supply cable to one or more required voltages to beutilized in the bar code reading device.

[0144] The automatic bar code reading device of the present inventionhas been described in great detail. Thus, it is appropriate at thisjuncture to illustrate the automatic hands-on and hands-free modes ofoperation of the system while utilized in different mountinginstallations.

[0145] In FIGS. 11A through 11D, a point-of-sale station is showncomprising an electronic cash register 6 operably connected to theautomatic bar code reading system of the present invention by way offlexible communication cable 7. Low voltage DC power is provided to thesystem by way of flexible power supply cable 8. In this particularmounting installation, scanner support stand 3 includes rubber feet 85Athough 85D and is supported on a horizontal countertop surface 90. Ifnecessary or desired in such mounting installations, base plate 70 maybe weighted by affixing one or more dense mass elements to the uppersurface of the base plate.

[0146] With automatic bar code reading device 2 supported within scannersupport stand 3 as shown in FIG. 11A, the system is automaticallyinduced into its automatic long-range hands-free mode of operation.However, owing to the positioning of both object detection and scanfields in this mounting installation, only bar code symbols located orsmall, very low profile objects can be easily read. In order to inducethe system into its short-range hands-on mode of operation, the usersimply encircles the handle portion of the hand-supportable device withhis or her fingers, and then lifts the device out of the scanner supportstand, as shown in FIG. 11B. With the automatic bar code reading deviceheld in the user's hand, and a bar coded object 91 in the other hand,the object is moved into the short-range portion of the object detectionfield as shown in FIG. 11C, where the object is automatically detectedand bar code symbol 92 automatically scanned by the visible laser beamrepeatedly, across the scan field. After the bar code symbol has beensuccessfully read and an audible and/or visible indication thereofproduced by successful read indicator 120, the bar code reading deviceis placed back within the scanner support stand, as shown in FIG. 11A,where it is once again induced into its long-range hands-free mode ofoperation.

[0147] In FIGS. 12A and 12B, the scanner support stand of the presentinvention is shown being installed on a vertical counter wall surface ofa point-of-sale station having an electronic cash register 6. As shownin FIGS. 12A and 13B, to install the scanner support stand, a pair ofspaced apart mounting screws 94A and 94B are partially screwed intovertical counter wall surface 93 so that base plate 70 will bevertically arranged slightly below horizontal countertop surface 95.Then, mounting holes 83A and 83B and screws 94A and 94B are passedthrough base plate 70, and then the base plate is slid down slightly andscrews 94A and 94B completely threaded into the vertical counter wallsurface. After attaching adaptor module 86 and flexible scanner,communication and power supply cables 5, 7, and 8 into their respectivejacks in the adaptor module, support frame 12 is snap fitted over themounted base plate, as shown in FIG. 12B, to provide an installedautomatic bar code reading system, as shown in FIG. 13.

[0148] With automatic bar code reading device 2 positioned withinscanner stand 3 as shown in FIG. 14, the system is automatically inducedinto its long-range hands-free mode of operation. In this configuration,bar code symbol 92 on object 91 can be easily read by the user graspingthe object and bringing it into the short-range portion of the objectdetection field, as illustrated in FIG. 14. Thereupon, the object isautomatically detected and bar code symbol 92 scanned by the visiblelaser beam repeatedly scanned across the scan field.

[0149] In order to read bar code symbols in the short-range hands-onmode of operation, the user grasps the handle portion of the bar codereading device as illustrated in FIG. 15A, and lifts it out of thescanner support stand. Then the user brings object 91 into theshort-range portion of the object detection field as illustrated in FIG.15B, so as to automatically detect the object and scan bar code symbol92 with the visible laser beam repeatedly moving across the scan field.After the bar code symbol has been successfully read and an audibleand/or visible indication thereof produced, the bar code reading deviceis placed back into the scanner support stand, automatically inducingthe system into its long-range hands-free mode of operation.

[0150] In FIGS. 16 through 17B, a point-of-sale station is showncomprising the automatic bar code reading system of the presentinvention operably connected to electronic cash register 6 by way offlexible communication and power supply cables 7 and 8. In thisparticular mounting installation, scanner support stand 3 is pivotallysupported above a horizontal counter surface 96 by way of a pivotaljoint assembly 97 connected to pedestal base 98 mounted under theelectronic cash register.

[0151] As more clearly illustrated in FIG. 18, pivotal joint assembly 97comprises a ball structure 99 joined to a mounting plate 100 by anextension 101. The pivotal joint assembly 97 also comprises asemispherical recess 102 formed in the end of a cylindrical support post103. As shown in FIG. 18A, a ball clamping element 104, havingsemispherical recess 105 and a bore 106, is connected to the distal endportion of support post 103 by an adjustment screw 107 passing throughbore 106 and threaded into a hole 108 in the distal end portion of thesupport post. By rotating knob 109 attached to adjustment screw 107,aligned semispherical recesses 102 and 105 can be sufficiently separatedapart to receive and retain ball structure 99. With this structuralarrangement, ball structure 99 can be securely clasped withinsemispherical recesses 102 and 105 at any desired orientation by simplytightening adjustment screw 107 with several turns of knob 109. Asillustrated in FIG. 18A, mounting plate 100 is fixedly connected to baseplate 70 by bolts 110A through 110D threaded through holes 111A through111D and 84A through 84D, respectively.

[0152] As illustrated in FIG. 18, the proximal end of support post 103is fixedly connected to the upper portion of pedestal base member 98A,by screw 112. In order to maintain the scanner support stand stationaryduring bar code reading operations, pedestal base member 98B is mountedunder electronic cash register 6. When installed in the mannerillustrated, scanner support stand 3 can be adjustably positioned andlocked into virtually any orientation in three-dimensional space, owingto the three principle degrees of freedom provided by the pivotal jointassembly. In FIGS. 16A, 18, 18B and 18C, these degrees of freedom areillustrated with respect to the Cartesian coordinate system shownembedded within the privotal joint assembly of the pedestal-mountedscanner support stand.

[0153] With automatic bar code reading device positioned within scannerstand 3 as shown in FIG. 16, the system is automatically induced intoits long-range hands-free mode of operation. By simply moving object 91into the object detection field, the bar code symbol 92 is repeatedlyscanned by the visible laser beam scanned across the scan field. Toinduce the automatic bar code reading system into its short-rangehands-on mode of operation, the user simply grasps the automatic barcode reading device and lifts it out of the scanner support stand, asillustrated in FIG. 17A. Then, by placing object 91 into the short-rangeportion of the object detection field, the object is automaticallydetected and bar code symbol 92 scanned by the visible laser beamrepeatedly, across the scan field. After the bar code symbol has beensuccessfully read and an audible and/or visible indication thereofproduced, the automatic bar code reading device can be placed back intothe scanner support stand, automatically inducing the system into itslong-range hands-free mode of operation.

[0154] Having described the preferred embodiment of the presentinvention, several modifications come to mind.

[0155] For example, in alternative embodiments of the present invention,the automatic hand-supportable device may not incorporate within itshousing, electronic circuitry for carrying out control, decoding otherdata processing functions; instead such electronic circuitry may becontained within a remote unit operably associated with thehand-supportable device by way of the flexible scanner cable. In thisembodiment, the hand-supportable device will function as an automatichand-supportable laser scanner. Alternatively, the housing may beadapted for hand-mounting.

[0156] The automatic bar code reading device and scanner support standof the present invention provides a fully automatic bar code readingsystem characterized by a automatic long-range hands-free andshort-range hands-on mode of operation, high-speed symbol recognition,and versatility.

[0157] The automatic hand-supportable bar code reading device of thepresent invention has been provided with a wide variety of complexdecision-making operations, endowing the system with a level ofintelligence hitherto unattained in the bar code symbol reading art.Within the spirit of the present invention, additional decision-makingoperations may be provided to further enhance the capabilities of thesystem.

[0158] While the particular illustrative embodiments shown and describedabove will be useful in many applications in code symbol reading,further modifications to the present invention herein disclosed willoccur to persons skilled in the art. All such modifications are deemedto be within the scope and spirit of the present invention defined bythe appended claims.

We claim:
 1. An automatic code symbol reading device comprising: (a) ahousing with an optically transmissive window through which opticalenergy can exit from, and enter into, the housing; (b) an optical energysource which, when activated by a controlling mechanism, produces anoptical beam projected through the optically transmissive window andinto a scan field extending outwardly from the housing; (c) a scanningmechanism which, when activated by the controlling mechanism, scans theoptical beam across the scan field to form a scanning pattern; (d) anoptical detector for detecting optical energy reflected from a codesymbol as the optical beam is scanned across the scan field and the codesymbol therein, and, in response to the detected optical energy,generating scan data indicative of the scanned code symbol; (e) anobject detector for detecting the presence of an object within an objectdetection field extending outwardly from the housing, and producing inresponse thereto an activation signal; (f) a processor for processingproduced scan data so as to decode the code symbol on the detectedobject, and upon detecting the code symbol, automatically producing datarepresentative of the decoded code symbol; and (g) a controllingmechanism for providing at least one of (i) timed activation of theoptical beam source and/or the scanning mechanism; and (ii) selection ofan operating range for the code symbol reading device.
 2. The automaticcode symbol reading device of claim 1, wherein the controlling mechanismincludes a timed activation mechanism for activating the optical beamsource and the scanning mechanism for up to a predetermined time periodin response to the generation of the activation signal; the timedactivation circuit deactivating the optical beam source and the scanningmechanism in response to the processor failing to decode the code symbolon the detected object within the predetermined time period.
 3. Theautomatic code symbol reading system of claim 2, wherein the objectdetector has a short-range mode of object detection and a long-rangemode of object detection, wherein, when the object detector is in theshort-range mode of object detection, the object detector is adapted todetect the presence of an object located within a short range asmeasured from the optically transmissive window, and wherein, when theobject detector is in the long-range mode of object detection, theobject detector is adapted to detect the presence of an object locatedwithin a long range as measured from the optically transmissive window.4. The automatic code symbol reading device of claim 3, wherein thecontrolling mechanism further comprises a mechanism for operating theobject detector in the short range mode of object detection in responseto the absence of a long range mode activation signal, and for operatingthe object detector in the long-range mode of object detection inresponse to the presence of the long range mode activation signal. 5.The automatic code symbol reading device of claim 3, wherein the housingincludes a head portion and a handle portion.
 6. The automatic codesymbol reading device of claim 1 wherein the object detector comprises:(a) a transmitter for transmitting an optical signal into the objectdetection field, and (b) a receiver for receiving at least a portion ofthe optical signal reflected by the object in the object detection fieldand for producing the activation signal in response thereto.
 7. Theautomatic code symbol reading device of claim 6 wherein the opticalsignal includes transmitted infrared radiation.
 8. The automatic codesymbol reading device of claim 1 wherein the code symbol is a bar codesymbol.
 9. The automatic code symbol reading device of claim 1 whereinthe object detector comprises a synchronous receiver/transmitter. 10.The automatic code symbol reading device of claim 1 wherein the housinghas a longitudinal dimension extending in a longitudinal direction, andwherein the scan field and the object detection field extend outwardbeyond the optically transmissive window in a direction substantiallyparallel to the longitudinal dimension of the housing.
 11. The automaticcode symbol reading device of claim 1, wherein the object detectionfield spatially encompasses at least a central portion of the scanfield.
 12. The automatic code symbol reading device of claim 1 whereinthe processor and the controlling mechanism are situated within thehousing.
 13. An automatic code symbol reading system comprising: (A) anoptical scanning device including (1) a housing having an opticallytransmissive window by which optical energy can exit from and enter intothe housing; (2) a data gathering mechanism for gathering data from acode symbol, the data comprising graphical indicia of differing lightreflectivities; the data gathering mechanism including: (a) an opticalenergy source for producing an optical beam projected into a scan fielddefined as extending from the housing; (b) a scanning mechanism forscanning the beam across the scan field in a manner so as to provide ascanning pattern; (c) an optical detector for detecting optical energyreflected by a code symbol as the beam is scanned across the scan fieldand the code symbol situated therein, and for automatically gatheringdata indicative of the detected optical energy, and (3) an objectdetector for detecting the presence of an object within an objectdetection field defined as extending from to the housing, and producingin response thereto an activation signal; (B) a processor for processinggathered data so as to decode the code symbol on the detected object,and upon decoding the code symbol, automatically producing symbolcharacter data representative of the decoded code symbol; and (C) acontrolling mechanism for controlling the operation of the automaticcode symbol reading system by providing at least one of: (a) timedactivation of the optical energy source and/or the scanning mechanism;and (b) selection of an operating range for the code symbol readingsystem.
 14. The automatic code symbol reading system of claim 13,wherein the object detector has at least a short-range mode of objectdetection and a long-range mode of object detection, wherein, when theobject detector is in the short range mode of object detection, theobject detector is adapted for detecting the presence of the objectlocated within a short range as measured from the optically transmissivewindow, and wherein, when the object detector is in the long range modeof object detection, the object detector is adapted for detecting thepresence of the object located within a long range as measured from theoptically transmissive window.
 15. The code symbol reading system ofclaim 14, wherein the controlling mechanism places the object detectorin the short range mode of object detection in response to the absenceof a long range mode activation signal at the activation mechanism, andplaces the object detector in the long range mode of object detection inresponse to the presence of the long range mode activation signal at theactivation mechanism.
 16. The automatic code symbol reading system ofclaim 13, wherein the controlling mechanism includes: an activationmechanism for activating the data gathering mechanism for up to apredetermined time period in response to a generation of the activationsignal; the activation mechanism deactivating the data gatheringmechanism in response to the processor failing to decode the code symbolon the detected object within the predetermined time period.
 17. Thecode symbol reading system of claim 16, wherein the object detectorcomprises: (a) a transmitter for transmitting an optical signal into theobject detection field, and (b) a receiver for receiving at least aportion of the transmitted optical signal that is reflected by theobject in the object detection field and for generating the activationsignal in response thereto.
 18. The automatic code symbol reading systemof claim 16 wherein the code symbol is a bar code symbol.
 19. Theautomatic code symbol reading system of claim 16 wherein the objectdetector comprises a synchronous receiver/transmitter.
 20. The automaticcode symbol reading system of claim 16 wherein the housing has alongitudinal dimension extending in a longitudinal direction, andwherein the scan field and the object detection field extend outwardbeyond the optically transmissive window in a direction substantiallyparallel to the longitudinal dimension of the housing.
 21. The automaticcode symbol reading system of claim 20, wherein the housing includes ahead portion and a handle portion.
 22. The automatic code symbol readingsystem of claim 16, wherein the object detection field spatiallyencompasses at least a central portion of the scan field.
 23. Anautomatic code symbol reading system comprising: (A) an optical scanningdevice including (1) a housing having an optically transmissive windowby which optical energy can exit from and enter into the housing; (2) adata gathering mechanism for gathering data from a code symbol, the datacomprising graphical indicia of differing light reflectivities; the datagathering mechanism including: (a) an optical energy source forproducing an optical beam projected into a scan field defined asextending from the housing; (b) a scanning mechanism for scanning thebeam across the scan field in a manner so as to provide a scanningpattern; (c) an optical detector for detecting optical energy reflectedby a code symbol as the beam is scanned across the scan field and thecode symbol situated therein, and for automatically gathering dataindicative of the detected optical energy, and (3) an object detectorfor detecting the presence of an object within an object detection fielddefined as extending from the housing, and producing in response theretoan activation signal, the object detection field having a volumetricextent; (B) a processor for processing gathered data so as to decode thecode symbol on the detected object, and upon decoding the code symbol,automatically producing symbol character data representative of thedecoded code symbol; and (C) a controlling mechanism for controlling theoperation of at least one of: the data gathering mechanism, the opticalenergy source, the scanning mechanism, and the optical detector, inresponse to the object detector detecting the presence of an object. 24.The automatic code symbol reading system of claim 23, wherein the objectdetector has at least a short-range mode of object detection and along-range mode of object detection, wherein, when the object detectoris in the short range mode of object detection, the object detector isadapted for detecting the presence of the object located within a shortrange as measured from the optically transmissive window, and wherein,when the object detector is in the long range mode of object detection,the object detector is adapted for detecting the presence of the objectlocated within a long range as measured from the optically transmissivewindow.
 25. The code symbol reading system of claim 24, wherein thecontrolling mechanism places the object detector in the short range modeof object detection in response to the absence of a long range modeactivation signal at the activation mechanism, and places the objectdetector in the long range mode of object detection in response to thepresence of the long range mode activation signal at the activationmechanism.
 26. The automatic code symbol reading system of claim 23,wherein the controlling mechanism includes: an activation mechanism forautomatically activating the data gathering mechanism for up to apredetermined time period in response to a generation of the activationsignal; the activation mechanism automatically deactivating the datagathering mechanism in response to the processor failing to decode thecode symbol on the detected object within the predetermined time period.27. The code symbol reading system of claim 26, wherein the objectdetector comprises: (a) a transmitter for transmitting an optical signalinto the object detection field, and (b) a receiver for receiving atleast a portion of the transmitted optical signal that is reflected bythe object in the object detection field and for generating theactivation signal in response thereto.
 28. The automatic code symbolreading system of claim 26 wherein the code symbol is a bar code symbol.29. The automatic code symbol reading system of claim 26 wherein theobject detector comprises a synchronous receiver/transmitter.
 30. Theautomatic code symbol reading system of claim 26 wherein the housing hasa longitudinal dimension extending in a longitudinal direction, andwherein the scan field and the object detection field extend outwardbeyond the optically transmissive window in a direction substantiallyparallel to the longitudinal dimension of the housing.
 31. The automaticcode symbol reading system of claim 30, wherein the housing comprises ahead portion and a handle portion.
 32. The automatic code symbol readingsystem of claim 26, wherein the object detection field spatiallyencompasses at least a central portion of the scan field.
 33. Theautomatic code symbol reading system of claim 23, wherein the processorand the controlling mechanism are situated within the housing.